The present invention relates to devices for injecting, infusing, administering, delivering and dispensing substances, and to methods for making and using such devices, as well as to related peripheral, adjunct, complementary, cooperative and auxiliary devices and methods. More particularly, the present invention relates to a needle unit for a syringe or injection device, such as a “pen” for self-medication by the patient, and to injection devices comprising such a needle unit.
Needle units, which in their delivered state surround an injection needle to protect a user from injury and which, once used, latch in a secure position in which they again surround the injection needle over its entire length, are known in the prior art. Typically, the needle surrounding structure can only be moved out of its latched state by force, which then results in the destruction of the needle unit. This secure connection after use is intended to protect against injury to the user after injecting, injury of the disposal staff when disposing of the needle units, and to provide that the needle unit is used properly and only once, so as to ensure the sterility of the needle unit when it is used.
EP 1 267 966 B1 discloses an injector cap for an ampoule support, said cap comprising a sliding sleeve which is mounted such that it can shift on it, wherein the sliding sleeve is pressed by a biasing means into a first, front position in which it hides a cannula. The sliding sleeve can be shifted, against the bias, into a second position in which the cannula emerges from the front facing end. A locking device is provided in the sliding sleeve which is slaved by the sliding sleeve on its way to the second position. Once the injection is complete, the biasing means presses the sliding sleeve back into its initial position in which it securely surrounds the cannula. The locking device is not slaved in this return movement, but rather latches on the cannula support. When the sliding sleeve is in its final position, the locking device establishes a secure connection via a locking means, which locks the sliding sleeve against shifting further.
One disadvantage of this injector cap is that the locking device has to be connected to the cannula support first, before it can lock the sliding sleeve against shifting further. This, however, also means that if the user does not slide the sliding sleeve back far enough, for example by employing too little force, the connection between the cannula support and the sliding sleeve is not established, hence the locking means is pressed back into the initial position again together with the sliding sleeve and the injector cap can thus continue to be used.